#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
#

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals

from thrift.Thrift import TType

import logging
_log = logging.getLogger('thrift.validator')

import sys
if sys.version_info[0] >= 3:
    basestring = str
    unicode = str
    long = int

class TValidator:
    tinfo = {
            # ttype: (type_name, python_type, min_value, max_value)
            TType.BOOL: ('BOOL', bool, None, None),
            TType.BYTE: ('BYTE', int, -128, 127),
            TType.DOUBLE: ('DOUBLE', float, None, None),
            TType.I16: ('I16', int, -32768, 32767),
            TType.I32: ('I32', int, -2147483648, 2147483647),
            TType.I64: ('I64', (int, long), None, None),
            TType.STRING: ('STRING', basestring, None, None),
            TType.UTF8: ('UTF8', unicode, None, None),
            }

    def __init__(self):
        self.custom_validators = {}

    def addClassValidator(self, name, validator):
        self.custom_validators[name] = validator

    def validate(self, msg):
        if not hasattr(msg, 'thrift_spec'):
            _log.error("Not a valid thrift object")
            return False

        name = msg.__class__.__name__
        return self.check_struct(name, msg, msg.thrift_spec)

    def check_basic(self, name, value, thrift_type):
        if thrift_type not in self.tinfo:
            _log.warn("%s Unrecognized thrift type %d. No validation done!",
                    name, thrift_type)
            return True

        t_name, python_type, v_min, v_max = self.tinfo[thrift_type]
        if not isinstance(value, python_type):
            error = "Value %s is not a %s" % (str(value), t_name)
        elif (v_min is not None and value < v_min) \
                or (v_max is not None and value > v_max):
            error = "Value %s not within %s boundaries" % (str(value), t_name)
        else:
            error = None

        if error is None:
            _log.debug("%s -> %s (type: %s) OK", name, str(value), t_name)
        else:
            _log.error("ERROR: %s is WRONG. %s", name, error)
        return error is None

    def check_map(self, name, value, k_type, k_specs, v_type, v_specs):
        _log.debug('%s - MAP check:', name)
        ok = True
        for k, v in value.items():
            if not self.check_type("%s key" % (name), k, k_type, k_specs):
                ok = False
            if not self.check_type("%s[%s]" % (name, k), v, v_type, v_specs):
                ok = False
        return ok

    def check_listset(self, name, value, v_type, v_specs):
        _log.debug('%s - LIST/SET check:', name)
        ok = True
        for i, v in enumerate(value):
            if not self.check_type("%s[%d]" % (name, i), v, v_type, v_specs):
                ok = False
        return ok

    def check_type(self, name, value, v_type, specs):
        if value is None:
            _log.debug("%s - NOT set", name)
            return True

        if v_type == TType.STRUCT:
            struct_specs = specs[1]
            ok = self.check_struct(name, value, struct_specs)
        elif v_type == TType.MAP:
            k_type = specs[0]
            k_specs = specs[1]
            v_type = specs[2]
            v_specs = specs[3]
            ok = self.check_map(name, value, k_type, k_specs, v_type, v_specs)
        elif v_type in (TType.LIST, TType.SET):
            v_type = specs[0]
            v_specs = specs[1]
            ok = self.check_listset(name, value, v_type, v_specs)
        else:
            ok = self.check_basic(name, value, v_type)

        return ok

    def check_struct(self, name, value, specs):
        _log.debug('%s - STRUCT check:', name)
        if specs is None:
            _log.error("%s - Empty thrift specs, can not be validated", name)
            return False

        ok = True
        for spec in specs:
            if spec is None:
                # Some fields of the struct might be not defined or
                # skipped old fields and their spec will be None
                continue
            f_name = name + "." + str(spec[2])
            f_type = spec[1]
            f_value = getattr(value, spec[2])
            f_specs = spec[3]
            if not self.check_type(f_name, f_value, f_type, f_specs):
                ok = False

        class_name = value.__class__.__name__
        if ok and class_name in self.custom_validators:
            if self.custom_validators[class_name](value):
                _log.debug('%s - Custom validator for class %s OK',
                    name, class_name)
            else:
                _log.error('%s - Custom validator for class %s failed!',
                        name, class_name)
                ok = False
        return ok
